The invention relates to a pneumatic device arranged to deliver a particulate material. One illustrative example of the device is to pneumatically deliver abrasive or polishing dental powder material. More particularly but not exclusively the invention is useful in so-called micro-airabrasion e.g. in dentistry.
It is one object of the invention to provide a device for this purpose which is clean and reliable and easy to maintain.
According to the invention in one aspect there is provided apparatus for pneumatically delivering particulate material, the apparatus comprising a pressure vessel having an outlet in the floor communicating with a flow of pressurised gas; a container for the particulate material to be delivered, the container being located in the vessel above the floor and having an outlet located to supply a small amount of particulate material to the outlet in the vessel floor; the container being arranged so that the material in the container is at substantially the same pressure as in the remainder of the vessel; and means for supplying pressurised gas in the vessel whereby the material is delivered via the vessel outlet at substantially uniform pressure.
Preferably the container is mounted within the vessel so that it may be surrounded by pressurised gas and the particulate material in the container is at substantially uniform gas pressure throughout its height. Most preferably the container is replaceable, and provided as an accessory. This can be sealed to avoid the risk of contamination before installation in the vessel.
Preferably at least the upper part of the container has translucent or transparent walls. When the container is mounted in a pressure vessel which protrudes above a housing the operator, e.g. a dentist, can easily see the level of material in the container.
Preferably the vessel is vibrated by a motor. Preferably the apparatus includes at least one switch arranged to energise or de-energise the motor in synchronism with the supply of pressurised gas.
Preferably the access to the interior of the vessel is via a top cap which has a pressure resistant seal, for example by a bayonet fitting arrangement.
In another aspect the invention provides a method of delivering particulate material pneumatically, the method comprising locating a container of the particulate material in a pressure vessel having an outlet in the floor, the outlet communicating with a flow of pressurised gas, the container having an outlet arranged to deliver a small amount of the particulate material to the vessel outlet; and supplying pressurised gas into the vessel to entrain particulate material from the container and substantially maintain pressurised gas in the vessel and one the particulate material in the container, whereby the material is delivered via the vessel outlet at substantially uniform pressure.
In another aspect, the invention provides a container for use in apparatus as defined, the container housing the particulate material, and having an exit port in the floor above a platform which together define an open sided chamber, the chamber being releasably sealed by a stopper, the top of the container also having a releasable seal.